Using mammalian cells cultured in vitro, biological intercomparisons will be made of the effectivenes of fast neutron beams at the Fermilab, Batavia, Illinois, and at the Cleveland Clinic. These are the two new facilities that are scheduled to augment the present United States neutron therapy effort. These beams will be compared with the presently used clinical facilities at Tamvec, NRL and Seattle. In addition, neutron intercomparisons are planned at Chiba, Japan, at the request of the U.S.-Japan cooperative cancer research program. Measurements of the oxygen enhancement ratio are planned at the University of Maryland cyclotron where neutrons are produced by bombarding a beryllium target with 101 MeV protons. Depending on the availability of a beam of adequate intensity, biological measurements will be started at the Los Alamos negative pi meson facility.